Wiring Notes
CPCI-405
Hardware-Manual • Doc.-No.: I.2306.21 / Rev. 3.5
Page 49 of 57
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6.3 Light Industrial Environment (Single Twisted Pair Cable)
6.3.1 General Rules
Note:
esd only grants the compliance with directive 2004/30/EC, if the CAN wiring is carried
out with single shielded double twisted pair cables that match the requirements of ISO
11898-2. See previous chapter: ’Heavy Industrial Environment (Double Twisted Pair
Cable)’.
The following general rules for CAN wiring with single shielded single twisted pair cable should
be followed:
1
A cable type with a wave impedance of about 120
±10% with an adequate conductor cross
section (
0.22 mm²) has to be used. The voltage drop over the wire has to be considered!
2
For light industrial environment use at least a two-wire CAN cable.
Connect
the two twisted wires to the data signals (CAN_H, CAN_L) and
the cable shield to the reference potential (CAN_GND).
3
The reference potential CAN_GND has to be connected to the functional earth (FE) at
exactly one point.
4
A CAN net must not branch (exception: short cable stubs) and has to be terminated with the
characteristic impedance of the line (generally 120
±10%) at both ends (between the signals
CAN_L and CAN_H and not at CAN_GND)!
5
Keep cable stubs as short as possible (l < 0.3 m)!
6
Select a working combination of bit rate and cable length.
7
Keep away cables from disturbing sources. If this cannot be avoided, double shielded wires are
recommended.
Figure. 4: CAN wiring for light industrial environment